The overarching goal of the proposed research is to examine the formation and temporal stability of extended family households among Mexican immigrants and Mexican-origin natives. The high levels of co-residence with extended kin among immigrants have led researchers and policy makers to view extended family support as a valuable resource for immigrants. But the social and economic value of extended family living arrangements is likely to depend in part on their stability. Social scientists currently know very little about the stability of extended family households and even less about the social and economic factors leading to their formation and stability because most work on extended living arrangements, and all prior work on the living arrangements of immigrants, has relied on cross-sectional data. The contribution of the proposed research is to use longitudinal data available from 1992, 1993, and 1996 panels of the Survey of Income and Program Participation (SIPP) to examine the extent to which Mexican immigrants and natives enter into and remain in extended family households, and to examine the social and economic determinants of entry into and duration of such living arrangements. The results of the research will provide insight into the social and economic value of extended family living arrangements among Mexican immigrants and natives. The research thus has important implications for the development and evaluation of those immigration and welfare policies that are based on the presumption of existing stable family support for new arrivals. The research is also of social scientific significance because it will provide a much clearer picture of the factors leading to the formation and dissolution of extended family households than has previously been provided with cross-sectional data. The proposed project focuses on a single large ethnic group, Mexicans, in order to place analytically helpful limits on group-level variation in preferences for co-residence and migration and settlement experiences. The research will serve as a springboard for a larger project examining the connection between economic well-being and living arrangements across multiple ethnic groups and the possibility that the benefits derived from co-residence differ by gender.